816 research outputs found
Data-Driven Moving Horizon Estimation Using Bayesian Optimization
In this work, an innovative data-driven moving horizon state estimation is
proposed for model dynamic-unknown systems based on Bayesian optimization. As
long as the measurement data is received, a locally linear dynamics model can
be obtained from one Bayesian optimization-based offline learning framework.
Herein, the learned model is continuously updated iteratively based on the
actual observed data to approximate the actual system dynamic with the intent
of minimizing the cost function of the moving horizon estimator until the
desired performance is achieved. Meanwhile, the characteristics of Bayesian
optimization can guarantee the closest approximation of the learned model to
the actual system dynamic. Thus, one effective data-driven moving horizon
estimator can be designed further on the basis of this learned model. Finally,
the efficiency of the proposed state estimation algorithm is demonstrated by
several numerical simulations.Comment: 12 pages,3 figure
Enhancing Control Performance through ESN-Based Model Compensation in MPC for Dynamic Systems
Deriving precise system dynamic models through traditional numerical methods
is often a challenging endeavor. The performance of Model Predictive Control is
heavily contingent on the accuracy of the system dynamic model. Consequently,
this study employs Echo State Networks to acquire knowledge of the unmodeled
dynamic characteristics inherent in the system. This information is then
integrated with the nominal model, functioning as a form of model compensation.
The present paper introduces a control framework that combines ESN with MPC. By
perpetually assimilating the disparities between the nominal and real models,
control performance experiences augmentation. In a demonstrative example, a
second order dynamic system is subjected to simulation. The outcomes
conclusively evince that ESNbased MPC adeptly assimilates unmodeled dynamic
attributes, thereby elevating the system control proficiency.Comment: 5 pages,3 figures,conferenc
Dynamical localization transition in the non-Hermitian gauge theory
Local constraint in lattice gauge theory provides an exotic mechanism
inducing disorder-free localization. However, the nonequilibrium dynamics in
the non-Hermition lattice gauge model has not been well understood. Here, we
investigate the quench dynamics of spinless fermions with nonreciprocal hopping
in the gauge field formed from the bond spins. Based on the
effective model from duality mapping, the non-Hermitian skin effect,
disorder-free localization-delocalization transition, and the real-complex
transition of eigenenergies are explored systematically. By identifying the
diverse scaling behaviors of quantum mutual information for fermions and spins,
we predict that the non-Hermition quantum disentangled liquid presents both in
localized and delocalized phase with completely different physical nature, the
first comes from the gauge field and the second originates from
the non-Hermitian skin effect. We finally show that the nonreciprocal
dissipation of fermions leads the quantum information flowing from the fermions
to spins. Our results provide new insights to the nonequilibrium dynamics in
the gauge field, and can be experimentally verified using ultracold atoms in
optical lattices.Comment: 13pages, 10 figure
Design and implementation of wire tension measurement system for MWPCs used in the STAR iTPC upgrade
The STAR experiment at RHIC is planning to upgrade the Time Projection
Chamber which lies at the heart of the detector. We have designed an instrument
to measure the tension of the wires in the multi-wire proportional chambers
(MWPCs) which will be used in the TPC upgrade. The wire tension measurement
system causes the wires to vibrate and then it measures the fundamental
frequency of the oscillation via a laser based optical platform. The platform
can scan the entire wire plane, automatically, in a single run and obtain the
wire tension on each wire with high precision. In this paper, the details about
the measurement method and the system setup will be described. In addition, the
test results for a prototype MWPC to be used in the STAR-iTPC upgrade will be
presented.Comment: 6 pages, 10 figues, to appear in NIM
Representing Volumetric Videos as Dynamic MLP Maps
This paper introduces a novel representation of volumetric videos for
real-time view synthesis of dynamic scenes. Recent advances in neural scene
representations demonstrate their remarkable capability to model and render
complex static scenes, but extending them to represent dynamic scenes is not
straightforward due to their slow rendering speed or high storage cost. To
solve this problem, our key idea is to represent the radiance field of each
frame as a set of shallow MLP networks whose parameters are stored in 2D grids,
called MLP maps, and dynamically predicted by a 2D CNN decoder shared by all
frames. Representing 3D scenes with shallow MLPs significantly improves the
rendering speed, while dynamically predicting MLP parameters with a shared 2D
CNN instead of explicitly storing them leads to low storage cost. Experiments
show that the proposed approach achieves state-of-the-art rendering quality on
the NHR and ZJU-MoCap datasets, while being efficient for real-time rendering
with a speed of 41.7 fps for images on an RTX 3090 GPU. The
code is available at https://zju3dv.github.io/mlp_maps/.Comment: Accepted to CVPR 2023. The first two authors contributed equally to
this paper. Project page: https://zju3dv.github.io/mlp_maps
Observation of prolonged coherence time of the collective spin wave of atomic ensemble in a paraffin coated Rb vapor cell
We report a prolonged coherence time of the collective spin wave of a thermal
87Rb atomic ensemble in a paraffin coated cell. The spin wave is prepared
through a stimulated Raman Process. The long coherence time time is achieved by
prolonging the lifetime of the spins with paraffin coating and minimize
dephasing with optimal experimental configuration. The observation of the long
time delayed-stimulated Stokes signal in the writing process suggests the
prolonged lifetime of the prepared spins; a direct measurement of the decay of
anti-Stokes signal in the reading process shows the coherence time is up to 300
us after minimizing dephasing. This is one hundred times longer than the
reported coherence time in the similar experiments in thermal atomic ensembles
based on the Duan-Lukin-Cirac-Zoller (DLCZ) and its improved protocols. This
prolonged coherence time sets the upper limit of the memory time in quantum
repeaters based on such protocols, which is crucial for the realization of
long-distance quantum communication. The previous reported fluorescence
background in the writing process due to collision in a sample cell with buffer
gas is also reduced in a cell without buffer gas.Comment: 4 pages, 4 figure
Learning Human Mesh Recovery in 3D Scenes
We present a novel method for recovering the absolute pose and shape of a
human in a pre-scanned scene given a single image. Unlike previous methods that
perform sceneaware mesh optimization, we propose to first estimate absolute
position and dense scene contacts with a sparse 3D CNN, and later enhance a
pretrained human mesh recovery network by cross-attention with the derived 3D
scene cues. Joint learning on images and scene geometry enables our method to
reduce the ambiguity caused by depth and occlusion, resulting in more
reasonable global postures and contacts. Encoding scene-aware cues in the
network also allows the proposed method to be optimization-free, and opens up
the opportunity for real-time applications. The experiments show that the
proposed network is capable of recovering accurate and physically-plausible
meshes by a single forward pass and outperforms state-of-the-art methods in
terms of both accuracy and speed.Comment: Accepted to CVPR 2023. Project page: https://zju3dv.github.io/sahmr
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